High mach deceleration device



United, States Patent 2,936,710 A men MACH DECELERATION DEVICE corporation of Delaware Application-January 3, 1956, Serial No. 556,874

3 Claims. (Cl. 102-50) This invention relates generally to aerodynamic'deceleration devices, and more particularlyto a high Mach deceleration device for increasing the drag on a missle in a longitudinal direction:-

' v "It is a primary object of this invention to provide a high Mach deceleration device which, upon operation, not

only increases the longitudinal drag on the missile but simultaneously spoils nose lift thereby increasing the stabilizing moment of the missile about its center of gravity.

Another important object is'to provide a decelerating device which will slow-a missile sufficiently to enable a parachute to be used and which is so designed that the possibility of the decelerating device fouling the parachute lines is avoided.

An auxiliary object of the invention is to' provide a deceleration device which simultaneously serves to protect measuring instruments or the like normally housed in the nose piece of the missile. 7

These and other objects and advantages of this invention are attained by providing a thin shell at the forward portion of themissile immediately preceding the nose cone. This shell is adapted to be telescoped over the nose cone by sliding; forward, to provide, in effect, a substantially flat nose shape. Not only is the longitudinal drag increased by a large numerical factor as a result' 'of this flat nose shape, but so positioning the shell over by referring to a preferred embodiment thereof as shown inthe accompanying drawings, in which:

Figure 1 is a perspective view of a high Mach missile in descending flight;

" Figure2 is a view of the missile of Figure 1 showing the decelerating device in its operative position;

,Figure 3 is a cut-away view partly in cross section of the missile taken in the direction of the arrows 3-3 of Figure 2; I

Figure 4 is a cross section taken in the direction of the arrows 4-4 of Figure 3; and, I

Figure. 5 is a cross section of a portion of the 'decelerating device taken in the direction of the arrows 5-5 of Fig. 3. 7

Referring to Figure 1, there is shown a missile 10 with a decelerating device 11 surrounding a forward portion of the missile immediately preceding the missile nose cone 12. As shown, the decelerating device 11 forms an aerodynamically clean surface with the missile fuselage 10 and nose piece 12. Preferably, the device William Bollay, Pacifie Palisades, Calif., assignor, by mesne assignments, to Curtiss-Wright. Corporation, a-

diameter'corresponding to the outside diameter of the adjacent portions of the missile.

In Figure 2, the cylindrical shell 11 is shown in its operative position for inducing high longitudinal drag. Any' suitable means may be employed fortelescoping the shell 11 over the nose cone 1 2. One means for effecting this movement comprises a series of piston rods, two of which are shown in Figure 2 at 13 and 14 and a third of which is shown in Figure 4 at 15. A minimum number of such rods would be three spaced i120 circumferentially about the forward portion of the missile, as shown in Figure 4, to insure balanced forces actingon the end of the shell with respect to its axis. a

As shown most clearly in Figure 3, the piston rods such as rods 13 and 14 are rigidly securedto the rear end of the shell 11 and terminate in pistons 16 and 17 operable'within piston cylinders 18 and 19 in the missile fuselage-10. The cylinders 18 and 19 arev connected'to a manifold passagei20 passing through a valve 21 to a high pressure source S. Alternatively, ram air pressure could be used as a pressure source.

The forward portion of the missile is provided with a 7 reduced diameter in order to accommodate the thickness 11 comprises a thin cylindrical shell having an outside 1 of the cylindrical shell 11 and thereby insure aerodynamic streamlining when the shell is retracted. As shown in Figures 3 and 4, this reduced portion is preferably provided with a series of longitudinal grooves 22, 23, and 24 corresponding to the number of piston rods and positioned to accommodate a portion of thepiston rod diameters. These grooves also serve as ball bearing races together with the inside cylindrical surface of the shell for accommodating three sets of ball bearings, one set within the groove 22 being designated 26. The rear end of the cylindrical shell to which the piston rods are afiixed includes three radially directed keys such as the key 25,

shown in Figs. Blend 5, which serve the dual functionof confining the respective sets of ball bearings in their respective grooves and guiding the shell in its longitudinal movement, by projecting partially into the grooves. The use of three sets" of ball bearings distributed circumferentially prevents any possibility of binding of the.

shell during its longitudinal movement.

In operation, assume that the missile is entering the atmosphere from a high altiude at a speed of Mach 15. I In response to either automatic timing mechanism withv in the missile or altitude sensitive means, high pressure from the source S is introduced into the cylinders by opening of valve 21 to urge the cylindrical shell 11 forwardly over the nose piece 12. It will be noted that the shell has a sharp leading edge and is of'relatively thin construction so that there is not a large aerodynamicf resistance offered to this movement. Forward motion of the shell 11 is checked when the piston heads 16 and 1'7 reach the end of the cylinders 18 and 19. In the operative position shown, static air will be trapped between the nose cone 12 and'the inside surrounding portion of the shell 11 so that an effectively flat nose shape results therebyvinducing an extremely high longitudinal drag on the missile. Further, all nose lift will be spoiled so that the:

It will thus be seen that the present invention provides 'a reliable and simplified means for decelerating a missile from a high Mach number to a low speed without rendering the missile unstable. Modifications within the scope Patented May. 17, 1960 and spirit of this invention will occur to those skilled in the art. The deceleration device is therefore not to be thought of as limited to the particular system described and shown for illustrative purposes.

What is claimed is:

1. In a missile having a generally cylindrical body including a forward portion terminating in a nose piece having a forward tip, a high Mach decelerating device for decelerating said missile, comprising: a shell of substantially the same outside diameter as the body of said missile, said shell having a front annular end surrounding said forward portion; and means for sliding said shell and nose piece relative to each other to bring said forward tip of said nose and said front annular end into substantially coplanar relationship so that said shell substantially surrounds said entire nose piece whereby the lift on said nose piece is spoiled.

2. A high Mach deceleration device for decelerating a missile, comprising, in combination: a missile body having a forward portion; a nose cone secured to said forward portion; a thin cylindrical shell surrounding said forward portion; and means for telescoping said shell from said forward portion over said nose cone to define between a substantial portion of the outside surface of said nose cone and the inside surface of said cylindrical shell an annular air pocket blocking the fiow of air between said outside surface of said nose cone and the inside surface of said cylindrical shell whereby the lift on said nose cone is spoiled.

3. A device according toclaim 2, in which said forward portion comprises a reduced diameter section defining, with the inside cylindrical surface of said shell, an annular space; bearing means in said annular space; said means for telescoping said shell comprising piston-cylinder means operatively connected to said shell and missile body; and a source of high pressure adapted to be connected to said piston-cylinder means.

References Cited in the file of this patent UNITED STATES PATENTS 1,295,047 Louden Feb. 18, 1919 2,357,680 Molloy Sept. 5, 1944 2,684,629 Nordfors July 27, 1954 

